Composite radiopaque intracorporeal product

ABSTRACT

The invention is directed to a guidewire having a distal flexible member, such as a helical coil, which is formed with at least one highly radiopaque component and at least one high strength component. In a presently preferred embodiment, the highly radiopaque component is at least 10% and less than about 60% of the transverse cross-section of the flexible member, preferably at least 20% but less than 40%. The highly radiopaque component may be formed of radiopaque material such as platinum, gold, iridium and the like and the high strength component may be formed of a material such as tantalum, stainless steel, NiTi alloys, Co—Cr—Mo alloys and the like.

BACKGROUND OF THE INVENTION

[0001] This is a divisional application of co-pending application havingSer. No. 09/995,196, filed Nov. 26, 2001, which is a continuation ofparent application having Ser. No. 09/098,443, filed Jun. 17, 1998, nowissued as U.S. Pat. No. 6,387,060, all of whose contents are herebyincorporated by reference.

[0002] This invention relates to the field of intracorporeal medicaldevices such as guidewires for advancing intraluminal devices includingstent delivery catheters, balloon dilatation catheters, atherectomycatheters and other intraluminal devices within a patient's body lumen.

[0003] Conventional guidewires for angioplasty, stent delivery,atherectomy and other vascular procedures usually comprise an elongatedcore member with one or more tapered sections near the distal endthereof and a flexible body such as a helical coil or a tubular body ofpolymeric material disposed about the distal portion of the core member.The flexible body may extend proximally to an intermediate portion ofthe guidewire. A shapable member, which may be the distal extremity ofthe core member or a separate shaping ribbon which is secured to thedistal extremity of the core member extends through the flexible bodyand is secured to the distal end of the flexible body by soldering,brazing or welding which forms a rounded distal tip. Torquing means areprovided on the proximal end of the core member to rotate, and therebysteer, the guidewire while it is being advanced through a patient'svascular system.

[0004] Further details of guidewires, and devices associated therewithfor various interventional procedures can be found in U.S. Pat. No.4,748,986 (Morrison et al.); U.S. Pat. No. 4,538,622 (Samson et al.):U.S. Pat. No. 5,135,503 (Abrams); U.S. Pat. No. 5,341,818 (Abrams etal.); and U.S. Pat. No. 5,345,945 (Hodgson, et al.) which are herebyincorporated herein in their entirety by reference thereto.

[0005] In a typical coronary procedure using a guidewire, a guidingcatheter having a preformed distal tip is percutaneously introduced intoa patient's peripheral artery, e.g. femoral or brachial artery, by meansof a conventional Seldinger technique and advanced and steered thereinuntil the distal tip of the guiding catheter is seated in the ostium ofa desired coronary artery.

[0006] There are two basic techniques for advancing a guidewire into thedesired location within a patient's coronary anatomy through thein-place guiding catheter. The first is a preload technique which isused primarily for over-the-wire (OTW) catheters and the second is thebare wire technique which is used primarily for rail type catheters.

[0007] With the preload technique, a guidewire is positioned within aninner lumen of an OTW device such as a dilatation catheter or stentdelivery catheter with the distal tip of the guidewire just proximal tothe distal tip of the catheter and then both are advanced through theguiding catheter to the distal end thereof. The guidewire is firstadvanced out of the distal end of the guiding catheter into thepatient's coronary vasculature until the distal end of the guidewirecrosses the arterial location where the interventional procedure is tobe performed, e.g. a lesion to be dilated or an arterial region where astent is to be deployed. The catheter, which is slidably mounted ontothe guidewire, is advanced out of the guiding catheter into thepatient's coronary anatomy over the previously introduced guidewireuntil the operative portion of the intravascular device, e.g. theballoon of a dilatation or a stent delivery catheter, is properlypositioned across the arterial location. Once the catheter is inposition with the operative means located within the desired arteriallocation, the interventional procedure is performed. The catheter canthen be removed from the patient over the guidewire. Usually, theguidewire is left in place for a period of time after the dilatation orstent delivery procedure is completed to ensure re-access to the distalarterial location if it is necessary. For example, in the event ofarterial blockage due to dissected lining collapse, a rapid exchangetype perfusion balloon catheter such as described and claimed in U.S.Pat. No. 5,516,336 (McInnes et al), can be advanced over the in-placeguidewire so that the balloon can be inflated to open up the arterialpassageway and allow blood to perfuse through the distal section of thecatheter to a distal location until the dissection is reattached to thearterial wall by natural healing.

[0008] With the bare wire technique, the guidewire is first advanced byitself through the guiding catheter until the distal tip of theguidewire extends beyond the arterial location where the procedure is tobe performed. Then a rapid exchange type catheter, such as described inU.S. Pat. No. 5,061,273 (Yock) and the previously discussed McInnes etal. patent, which are incorporated herein by reference, is mounted ontothe proximal portion of the guidewire which extends out of the proximalend of the guiding catheter and which is outside of the patient. Thecatheter is advanced over the guidewire, while the position of theguidewire is fixed, until the operative means on the rapid exchange typecatheter is disposed within the arterial location where the procedure isto be performed. After the procedure the intravascular device may bewithdrawn from the patient over the guidewire or the guidewire advancedfurther within the coronary anatomy for an additional procedure.

[0009] An important attribute for guidewires is having sufficientradiopacity to be visualized under a fluoroscope, allowing the surgeonto advance the guidewire to a desired intraluminal location,particularly the distal extremity of the guidewire. Unfortunately, themost suitable materials for guidewires, such as stainless steel and NiTialloys, exhibit relatively low radiopacity. Accordingly, variousstrategies have been employed to overcome this deficiency. Portions ofthe guidewire, usually the shapeable distal tip, are typically made fromor coated with highly radiopaque metals such as platinum, iridium, goldor alloys thereof. For example, a 3 to 30 cm platinum tip-coil isfrequently soldered to the distal extremity of the guidewire. An obviousdrawback of these prior art methods is the high expense and scarcity ofhighly radiopaque metals and the difficulty and expense of manufacturingproducts from these materials. The requirement of both a high degree ofradiopacity, high strength and flexibility can present design problems.

[0010] Accordingly, there remains a need for guidewires havingsufficient radiopacity to allow visualization under a fluoroscopewithout the extensive use of expensive radiopaque metals such asplatinum, gold, iridium and the like.

INVENTION SUMMARY

[0011] The present invention is directed to an intracorporeal devicesuch as a guidewire having an elongate core member with a proximal coresection and a distal core section and a flexible body such as a helicalcoil formed of metallic wire which is disposed about and secured to atleast a portion of the distal core section.

[0012] In accordance with the invention, the intracorporeal product hasa body with multi-components, at least one highly radiopaque componentand at least one high strength component having less radiopacity thanthe highly radiopaque component. The amount of the highly radiopaquecomponent and the high strength component of the flexible body dependsupon the radiopacity of each of the components. Generally, however, thehighly radiopaque component should be at least about 10% but not be morethan about 60%, preferably about 20% to about 40%, of the totaltransverse cross-section of the flexible body. The greater radiopacitythe high strength component has, lessens the amount of the expensivehighly radiopaque material which is needed.

[0013] The highly radiopaque material of the coil may be selected fromthe group of platinum, gold, iridium, highly radiopaque alloys thereof.The presently preferred highly radiopaque material is an alloy of90%(wt) PI and 10%(wt.) Ir. The high strength material of the coil maybe selected from the groups consisting of radiopaque materials such astantalum, tungsten and silver and non-radiopaque materials such asstainless steel, NiTi alloys and Co—Cr—Mo alloys. Tantalum and alloysthereof are preferred because these materials have significantradiopacity in addition to being high strength and can moresignificantly reduce the amount of expensive radiopaque material whichmuch be used for a particular degree of radiopacity. For example, asolid wire of 90% platinum -10% iridium will provide completeradiopacity, whereas, a wire of the same thickness with 70% tantalumcore and 30% of a 90% Pt-10% Ir alloy cladding will provided the samedegree of radiopacity but substantially improved mechanical properties.The use of non-radiopaque high strength metals will provide a fairradiopacity with adequate or improved mechanical properties dependingupon the material used. A thickness of about to about 10 micrometers ofhighly radiopaque material will usually provide complete radiopacity forintracorporeal use with conventional fluoroscopic observation.

[0014] The presently preferred form of the flexible body which issecured to the distal core section is a two component metallic wiremember such as a helical coil. Other forms include a multi-wire braidformed of two-component metallic wires. In one presently preferredembodiment, the two-component wire is made of a highly radiopaquecladding and a relatively high strength material. In this way, theradiopaque material of the cladding can be chosen for its radiopaqueproperties and the core material can be chosen for strength propertiesthat enhance the guidewire's performance. Alternatively, the corematerial may be highly radiopaque and the cladding may be formed of thehigh strength material.

[0015] The distal end of the helical coil may attached directly orindirectly to the distal end of the core member and it may also besecured to the core member at one or more proximal locations.

[0016] In order to increase the flexibility of the distal section of theguidewire, the core member of the guidewire may be formed in aconventional manner with a distal section having at least one taperedsegment, wherein the elongate core member tapers distally to reducedtransverse dimensions. If desired, the one or more distally taperedsegments of the distal section of the elongate core member may be markedwith radiopaque markers to indicate where a tapered segment begins orends. In this way, a physician using the guidewire is able to identifythe relative flexibility and stiffness of an area of interest on theguidewire using fluoroscopic imaging.

[0017] A second or proximal coil formed of helically shaped wire may beprovided proximal to the radiopaque first coil which is formed of lessradiopaque material. The wire forming the second coil may have acircular transverse cross-section or a substantially rectangular crosssection. A coil of wire having a rectangular cross section providesincreased stiffness and coil integrity as compared to wire with a roundcross section of similar thickness, due to the increased cross sectionalarea. The proximal end of the second coil is attached to the distalsection of the elongate core member by means of adhesive, solder and thelike. The distal end of the second coil is preferably secured to thedistal section of the core member by the same mass of solder or the likethat secures the proximal end of the first, highly radiopaque coil tothe core member.

[0018] The flexible body of the present invention has at least adequateradiopacity and strength while being substantially cheaper to make thansimilar structures with helical coils formed of precious metal such asplatinum and gold. By appropriately choosing the materials, propertiescan be obtained which are better than conventional products, whilesignificantly reducing costs.

[0019] These and other advantages of the invention will become moreapparent from the following detailed description of the invention whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a schematic elevational view, partially in section, of aguidewire which embodies features of the invention.

[0021]FIG. 2 is a transverse cross-sectional view of the guidewire shownin FIG. 1 taken along the lines 2-2.

[0022]FIG. 3 is an enlarged longitudinal cross-sectional view of theguidewire shown in FIG. 1 within the circle 3.

[0023]FIG. 4 is an elevational view partially in section of analternative guidewire wherein the distal tip of the core member isflatten and extends and is secured to the distal end of the coil.

[0024]FIG. 5 is a transverse cross-sectional view of the guidewire shownin FIG. 4 taken along the lines 5-5.

[0025]FIG. 6 is a longitudinal cross-sectional view of an alternativeguidewire design which has a proximal coil with a rectangular transversecross-section.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] FIGS. 1-3 illustrate a guidewire 10 having features of thisinvention that generally include an elongated core member 11, with aproximal core section 12 and a distal core section 13 and a distal,highly radiopaque helical coil 14 disposed about and secured to thedistal extremity of the core member. A shaping ribbon 15 extends fromthe distal end of the core member 11 and is secured to the mass ofsolder or weldment forming the rounded distal tip 16 of the guidewire.The proximal end of the shaping ribbon 15 is secured to the distal endof the core member 11 by suitable means such as solder, brazement,weldment or adhesive. The proximal end of the distal highly radiopaquecoil 14 is secured to the core member 11 by mass 17 which may be solder,brazement, weldment or adhesive. A second or proximal coil 18 is securedby its distal end to the core member by the same mass that secures theproximal end of the distal highly radiopaque coil 14 to the core member11. The proximal end of the proximal coil 18 is secure to the coremember by solder, brazement, weldment or adhesive 20. The proximal endof the distal coil 14 and the distal end of the proximal coil 18 arepreferably threaded together at the site 17 of securing these ends tothe core member 11.

[0027] The core member 11 of the guidewire 10, as shown in FIG. 1,generally may have conventional features with conventional dimensions.The proximal core section has a relatively constant or uniformtransverse cross-sectional dimensions and the distal core section 13 hasa first taper 21, a second taper 22 and a third taper 23 which taper inthe distal direction to smaller transverse cross-sectional dimensions.An first intermediate uniform dimensioned core portion 24 extendsbetween the first and second tapers 21 and 22 and a second intermediateuniform dimensioned core portion 25 extends between the second taper 22and the third taper 23.

[0028] As shown in more detail in FIG. 3, the distal highly radiopaquecoil 14 has an inner portion 26 and an exterior portion 27. The innerportion or core 26 of coil 14 is formed of high strength metallicmaterial such as stainless steel, NiTi alloy, Co—Cr—Mo alloys such asElgiloy or MP35N and tantalum (or alloys thereof). Tantalum is presentlypreferred because it also has a high degree of radiopacity in additionto high strength. The exterior portion or cladding 27 is formed of ahighly radiopaque metallic material such as platinum, gold, iridium,palladium, tantalum, tungsten, silver and highly radiopaque alloysthereof. If desired these components forming the wire of coil 14 may bereversed, i.e. the inner portion 26 may be highly radiopaque and thecladding 27 may be formed of high strength material.

[0029]FIG. 4 illustrates a guidewire 30 which has various alternativeembodiments. The first alternative embodiment is the core member 31having a flattened distal extremity 32 (instead of a shaping ribbon)which extends and is secured to the rounded mass 33 of solder,brazement, weldment or adhesive which is secures the distal end of thedistal, highly radiopaque coil 34 thereto. The proximal helical coil 35may be formed of conventional stainless steel wire. As in the embodimentshown in FIGS. 1 and 3 the distal end of the second proximal coil 35 issecured to the core member 31 at the same location 36 as the proximalend of the distal, highly radiopaque coil 34. The distal, highlyradiopaque coil 34, as shown in FIG. 5 is formed of an inner component37 of highly radiopaque material and an outer component 38 of highstrength material.

[0030] Another alternative design is depicted in FIG. 6. In this design,the guidewire 40 has a core member 41 with a flattened distal extremity42 as in the embodiment shown in FIG. 4. While not shown in detail thedistal coil 43 has a highly radiopaque cladding and a high strength coreas described for the embodiment of FIGS. 1-3. However, the proximal coil44 disposed about the core member 41 has an essentially rectangularshaped transverse cross-section as compared to the circular transversecross-section of the distal coil 43. The rectangular transversecross-section provides additional support. This guidewire design isprimarily for peripheral arteries and generally has larger dimensionsthan the embodiments shown in FIGS. 1-5.

[0031] Another alternative design is depicted in FIG. 6 In this design,the guidewire 40 has a core member 41 with a flattened distal extremity42 as in the embodiment shown in FIG. 4. While not shown in detail thedistal coil 43 has a highly radiopaque cladding and a high strength coreas described for the embodiment of FIGS. 1-3. However, the proximal coil44 disposed about the core member 41 has an essentially rectangularshaped transverse cross-section as compared to the circular transversecross-section of the distal coil 43. The rectangular transversecross-section provides additional support. This guidewire design isprimarily for peripheral arteries and generally has larger dimensionsthan the embodiments shown in FIGS. 1-5.

[0032] The clad wire forming the distal coil may be formed in a varietyof ways. The presently preferred manner is to prepare a tubular memberof one of the components and a solid core (e.g. wire or rod) of theother component suitably sized so that the tubular member formed of onecomponent can be co-drawn with the solid core of the other component toflow with the latter to form a strong bond. It is presently preferred toform the tubular member of the highly radiopaque material and the coremember of the high strength material with a lesser radiopacity. Othermeans for forming the clad wire for the distal coil include plasmaspraying one component onto a wire or rod of the other component.Physical vapor deposition may also be employed in a similar manner.Electroplating and other more conventional methods may be used to formthe clad product.

[0033] Generally, the overall length of the guidewire may range fromabout 80 to about 320 cm, preferably about 160 to about 200 for coronaryuse. Typically, commercial guidewire products of the invention will comein standard lengths of 175, 190 and 300 cm. The distal section of theguidewire is about 1 to about 10 cm, preferably about 2 to about 5 cm inlength, the intermediate section is about 15 to about 50, preferablyabout 25 to about 40 cm in length. The outer diameter of the guidewiremay vary depending upon use, but typically is about 0.008 to about 0.035inch (0.2-0.9 mm). The lengths and diameters of the tapers may likewisevary. The composite wire forming the proximal and distal coils willtypically have a diameter of about 0.002 to about 0.006 inch (0.051-0.15mm). A 0.002 inch diameter composite wire is typically used for forminga coil of about 0.010 to about 0.014 inch (0.25-0.36 mm) in diameter, a0.0025 inch (0.063 mm) wire for a coil with an OD of 0.0014 inch and awire of 0.0055 inch (0.14 mm) for larger OD coils. To the extent nototherwise described herein, the dimensions, constructions and materialsof the guidewire may be conventional.

[0034] Although individual features of embodiments of the invention maybe shown in some of the drawings and not in others, those skilled in theart will recognize that individual features of one embodiment of theinvention can be combined with any or all the features of anotherembodiment. Various modification may be made to the invention withoutdeparting from the scope thereof.

We claim:
 1. A process for providing a guidewire for intraluminal use ina medical procedure, comprising: providing an elongated core memberhaving a proximal core section and a distal core section; forming aflexible body by co-drawing a wire having an exterior of a firstradiopacity, and a high strength interior of a second radiopacity,wherein the first radiopacity is greater than the second radiopacity;wherein the exterior of the wire includes a material selected from thegroup consisting of platinum, palladium, iridium, and alloys thererof;wherein the high strength interior includes a material selected from thegroup consisting of tantalum, tungsten, and alloys thereof; anddisposing the flexible body on the distal core section.
 2. The processof claim 1, wherein the flexible body includes a coil.
 3. The process ofclaim 1, wherein the high strength interior further comprises a materialselected from the group consisting of nickel-titanium, Co—Cr—Mo, andalloys thereof.
 4. The process of claim 1, wherein the exterior of thewire is an alloy including 90% (wt.) platinum and 10% (wt.) iridium. 5.A process for providing a guidewire for intraluminal advancement of amedical device within a patient, comprising: providing an elongated coremember having a proximal core section and a distal core section;providing a first coil by cladding a highly radiopaque exteriorincluding a material selected from the group consisting of platinum,palladium, iridium, and alloys thereof, over a high strength interiorincluding a material selected from the group consisting of tantalum,tungsten, and alloys thereof, to form a wire, wherein the highlyradiopaque exterior of the wire has a transverse cross-section of atleast 10% of the first coil; disposing the first coil at the distal coresection; and disposing a second coil at the distal core section andproximal to the first coil.
 6. The process of claim 5, wherein the coremember includes a flattened distal tip.
 7. The process of claim 5,wherein the distal core section includes a taper in a distal direction.8. The process of claim 5, wherein the distal core section includesnickel-titanium.
 9. The process of claim 5, wherein the second coilincludes a non-circular, polygonal cross-sectional shape.
 10. A processfor providing a flexible body for an intracorporeal device, comprising:forming a wire at least partially into a helical coil having a highstrength interior core, and a highly radiopaque cladding that is atleast 10% but not more than 60% of a cross-sectional area of theflexible body.
 11. The process of claim 10, wherein the materials forthe cladding and the interior core are reversed.
 12. The process ofclaim 10, wherein the high strength interior core includes a materialselected from the group consisting of nickel-titanium, Co—Cr—Mo,tantalum, tungsten, and alloys thereof.
 13. The process of claim 10,wherein the process includes joining the flexible body to a secondflexible body.
 14. The process of claim 13, wherein the second flexiblebody is formed by co-drawing a wire having an exterior of a firstradiopacity and a high strength interior of a second radiopacity,wherein the first radiopacity is greater than the second radiopacity.